Single-atom metal-incorporated carbon nanomaterials (CMs) have shown great potential towards broad catalytic applications. In this work, we show that N-doped porous CMs embedded with redox-able Zn atoms exhibit superior capacitive performance. High Zn (~ 2.72 at.%)/N (~ 12.51 at.%) doping were realized by incorporating Zn²⁺ and benzamide into the condensation and carbonization of formamide and subsequent annealing at 900 °C. The Zn and N species are mutually benefited during the formation of ZnN₄ motif. The as-obtained Zn₁NC material affords a very large capacitance of 621 F·g⁻¹ (at 0.1 A·g⁻¹), superior rate capability (~ 65% retention at 100 A·g⁻¹), and excellent cycling stability (0.00044% per cycle at 10 A·g⁻¹). These merits are attributed to the high Zn/N loading, atomic Zn-boosted pseudocapacitive behavior, large specific surface area (~ 1,085 m²·g⁻¹), and rich pore hierarchy, thus ensuring both large pseudo-capacitance (e.g., ~ 37.9% at 10 mV·s⁻¹) and double-layer capacitance. Besides of establishing a new type of high Zn/N-loading carbon materials, our work uncovers the capacitive roles of atomically dispersed metals in CMs.

Carbon materials featuring hierarchical pores and atomically dispersed metal sites are promising catalysts for energy storage and conversion applications. Herein, we developed a facile strategy to construct functional carbon materials with a fluffy peony-like structure and dense binary FeCo-N_x active sites (termed as f-FeCo-CNT). By regulating the metal content in precursors, a three-dimensional (3D) interconnected conductive carbon nanotubes network was in-situ formed throughout the atomically dispersed FeCo-NC matrix during pyrolysis. Taking advantage of rich pore hierarchy and co-existence of highly active FeCo-N_x sites and beneficial FeCo alloy nanoparticles, the f-FeCo-CNT material exhibited excellent bifunctional performance towards oxygen reduction reaction/oxygen evolution reactions (ORR/OER) with respect to the atomically dispersed FeCo-NC (SA-f-FeCo-NC) and commercial Pt/C+RuO₂ mixture, surpassing the SA-f-FeCo-NC with a 20 mV higher ORR half-wave potential and a 100 mV lower OER overpotential (at 10.0 mA/cm²). Remarkably, the f-FeCo-CNT-assembled Zn-air battery (ZAB) possessed a maximum specific power of 195.8 mW/cm², excellent rate capability, and very good cycling stability at large current density of 20.0 mA/cm². This work provides a facile and feasible synthetic strategy of constructing low-cost cathode materials with excellent comprehensive ZAB performance.